1. Field of the Invention
The invention relates to a twin-schaft screw-type extruding machine, in particular a twin-shaft extruder, comprising a casing, two intersecting casing bores parallel to each other, a feed opening at one end of the casing and a discharge opening at the other end of the casing, two shafts disposed in the casing bores and driven to rotate in the same direction of rotation, screw elements disposed non-rotatably on the shafts, and mixing elements facing each other and associated in pairs, which are disposed non-rotatably on the shafts.
2. Background Art
Various mixing elements of different arrangements are used for the admixture of fillers and reinforcing agents into twin-shaft extruders. Owing to their dispersing and distributive mixing effect, these mixing elements lead to a homogeneous admixture of the fillers and reinforcing agents into a plastics matrix. When reinforcing fillers such as glass fibers are added to a plastics matrix, the length of the individual fibers should be reduced as little as possible for the final product to exhibit as good as possible mechanical properties. This is encountered by the demand for thermal and mechanical homogeneity of the product. The known mixing elements have not succeeded in attaining the effect of little damages to the fibers and sufficient homogeneity, the dispersing portion of these known mixing elements being too high.
A continuous mixer is known from U.S. Pat. No. 3,195,868 to have two parallel, intersecting casing bores in a casing. Each casing bore is provided with a shaft to be driven in the same direction of rotation. Mixing elements assigned to each other by twos are disposed on the shafts and are provided with mixing wings interengaging during rotation. These mixing wings are attached to paddle-type disks in the form of kneading blocks. They allow the material to pass though the housing unhampered in the conveying direction.
A similar design of kneading blocks is known from U.S. Pat. No. 4,752,135.